Time delay switching device



March 28, 1967 A. G. WRIGHT TIME DELAY SWITCHING DEVICE Filed April 18,1966 lll I N VEN TOR.

ARTHUR GEORGE WRIGHT ATTORNEXS United States Patent O This applicationVis a continuation-in-part application of my patent application Ser. No.344,949, now abandoned, tiled in the U.S. Patent Oice on Feb. 14, 1964.

This invention relates to a switching device for use in electricalcircuits, more particularly, it relates to a time controlled safetyswitching device which serves as a circuit component in the circuit itcontrols.

Prior art time controlled switching devices are ordinarily enclosed in acapsule having-a switch gap and in operation a time controlled connectorelement for the points of the switch gap is released to connect thepoints of the switch gap after a pre-determined time. In these devices`conducting lines from each branch of an outside circuit are connectedto the points of the switch gap so that'the connector element is theonly element enclosed in the capsule which becomes a part of the outsidecircuit. In other words, the capsule itself does not serve as a link inthe circuit when the circuit is closed so that the current does not passthrough the capsule from end to end.

There are a large number of applications wherein it is desirable to usethe capsule itself as a link in the circuit so that the use of circuitseparate from the capsule is avoided. For example, in the use ofexplosives in oil wells wherein a time actuated bridge wire detonatesthe explosive it is desirable to use a conducting cable in a detonatingcircuit to lower the explosive to the point of use. It is advantageousto have a switching device incorporated in the cable which becomes alink in the circuit when the switch is closed. This arrangementeliminates the use of extraneous circuits, outside wires and othercircuit components.

Accordingly, `it is an object of this invention to provide Va timecontrolled switching device which can be used in any type electricalcircuit.

It is another object of this invention to provide an encapsulatedswitching device in which the capsule serves as a link in the circuit sothat the circuit passes entirely through the capsule when it is closed.

It is another object of this invention to provide a switching devicewhich can be incorporated as a link in a circuit including a conductingcable used for supporting objects.

It is another object of this invention to provide a switching devicehaving a safety feature insuring that a circuit will be closed for aperiod of short duration only before it is reopened.

It is another object of this invention to provide a time controlledswitching device in which the time period can be accurately and reliablycontrolled.

It is another object of this invention to provide a time controlledsafety switching device which is adapted for use in a large number ofapplications and has a minimum of operating parts.

The above and other objects are accomplished by an encapsulatedswitching device comprising an insulating housing closed at both endswith conducting caps, each cap being electrically connected to terminalsinside the rice capsule, the terminal being spring biased toward theircontact positionV and held in normally open position by a timing elementso that upon elapse of a predetermined time the terminals are broughtinto contact. For providing a safety feature one of the terminalscarriesan insulating sleeve distal to its point of electrical contact with theother terminal so that after an instantaneous electrical contact of theterminals upon actuation of the timing means further relative movementbetween them is provided by the biasing means to cause breaking of thecircuit by means of the insulating sleeve. In the preferred modificationone of the terminals is in the form of a conducting plunger carrying aninsulating sleeve distal to its contact point with the other terminaland the other terminal is in the form of a switch gap carried by apiston biased in the direction of the plunger and held in biasedposition by the timing means so that upon actuation of the timing meansrelative movement of the terminals causes the plunger to instantaneouslycontact the points of the switch gap followed by movement of the Ypoints in the direction of the plunger to contact the insulating sleeveto break the circuit. It is `an important feature of the invention thatthe terminals are in electrical connection with the caps so that thedevice itself forms a link in the circuit when the switch is closed, andthe current travels through the device from end to end.

The invention will now be explained with reference to the drawingwherein FIG. 1 is a horizontal cross-sectional view of the switchingdevice of the invention with the switch in open position and showing theclosed position of the plun'ger in dotted lines;

FIG. 2 is a view similar to that of FIG. l showing the switch in thesafe position, and

FIG. 3 is a vertical cross-sectional view taken on the line 3 3 of FIG.l looking in the direction of the arrows.

In the figures like parts are identified by like numerals with primes Inthe description which follows only one of like members will be referredto and the numbers with primes will not be mentioned.

The elements of the switching device are enclosed in a housing lll ofinsulating non-conducting material, suchl as, polyethylene, Teflon orother type plastic. The material of the housing should be inert toordinary solvents at least as it may come in contact with a wide varietyof solvents. Steps 12 and seating surface 14 are formed at the end ofthe housing by machining or molding techniques. A connector sleeve 16 ofconducting material, preferably metal, is press itted over seatingsurface 14. The connecting sleeve 16 may be fitted over seating surface14 by various means but it should be seated so that 4a fluid-type sealis effected between it and the seating surface. The connector sleeve 16is provided with external threads 18.

As used in this specilication and in the claims, the term conductingmaterial includes metals, alloys, metal impregnated plastic, etc.

The housing 10 is closed -at either end by a cap 20 having internalthreads 22 mating with external threads 1 8 of the connector sleeve 16.The cap 20 is of conducting material as it is in the circuit path ofcurrent which travels through the switching device. An O ring 24 ofelastic material, such as rubber, is seated between cap 20 and the endof connector element 16. The pur- 3 pose of this O ring is to insurethat the interior of the housing is uid tight.

A boss or plunger seat 26 is formed on the interior surface of cap 20and supports plunger 2S which may be made integrally with the boss 26.The boss and plunger are of conducting material as they are componentsof an electrical circuit. The plunger 28 is bulletshaped at its upperend 29 and is constructed to come to a point at the end as shown. Ahollow insulating sleeve 30 is carried by the plunger. The insulatingsleeve 30 may be made of suitable non-conducting material, such asvarious type plastics. It plays an important role in the safety featureof the invention and serves as a circuit breaker to break the currentpath through the switching device.

A movable electrode piston 32 is included in the housing beyond theplunger 28. The piston in the modification shown is of metal or otherconductor as it serves as an element of an electrical circuit. Thepiston 32 is constructed with a hollow interior in which is seated aninsulating liner 35 constructed with a cone-shaped inner chamber withthe hollow pointed end designed to seat the end 29 of plunger 28. Theend of piston 32 adjacent the plunger 29 is flared and a seat 36 isconstructed in the flared portion to receive a pellet or time tablet 37.The pellet 37 serves as a timer to permit actuation of the switchmechanism to the closed and safety position. It is of solublenon-conducting material. lt must be of nonconducting material because itholds the switch in open position. It must be soluble in a wide range ofsolutions or solvents which may be placed in the housing for dissolvingor disintegrating it.

The pellet may be constructed of a wide range of materials and is notrestricted to any particular material. A pellet constructed of aspirin,for example, would be suitable when used in connection with a solventlike water. The time period for actuation of the switch is governed bythe material, density and solubility of the pellet and the solvent inconjunction with which it is used. There are other factors which varythe time period for actuation of the switch, such as, the concentrationof the solvent, the size of the pellet, etc., but these are all withinthe skill of the art. A pellet-solvent combination which has been foundto be effective is a product sold on the market as Dow Resin PS-3, apolystyrene resin made by the Dow Chemical Company of Midland, Michigan,and a solution of methylene chloride. Various solvents which may be usedwith a suitable pellet material are aliphatic naphthas, aromaticsolvents, ketones, ethers, acetates, alcohols, glycols, glycol ethers,amines, chlorinated solvents, water, and others. Examples of the widevariety of materials which may be used for the material of the pelletwith suitable solvents are waxes, epoxy resins, polystyrene resins,silicone resins, phenolic and phenol-formaldehyde resins,glycerin-esterified resins, chlorinated rubber, vinyl resins, andothers. The invention broadly includes the use of a pellet of solidmaterial and a solvent in which it dissolves or disintegrates. It is notrestricted to any particular pellet material or solvent as, obviously,any pellet material and a solvent in which it dissolves or disintegratesis a suitable combination. Gases and other means may be used fordisintegrating the pellet. It is only necessary that the solution ordisintegration of the pellet be controllable.

A spring seat 38 is machined in the outer surface of piston 32 on eitherside and a spring 39 of conducting material is mounted therein by meansof screw 40 inserted in the wall of piston 32. Conducting contact point4l is attached to the inner side of spring 39 and extends through thewalls of piston 32 and sleeve 35. A switch gap is formed between theends of contact points 4l and 41'. The spring must be of conductingmaterial as it is in a current path to the switch and is an element of acircuit. Horizontal channels 42 are machined in the outer surface of1piston 32 and circumferentially spaced around the piston.Longitudinally spaced ducts or bores 43 connect these channels with theinterior of the piston. A boss i6 made integral with piston 32 isprovided on the end of the piston distal to the plunger 255. The boss 46is constructed with an inner channel 48 and an outer circumferentialseating groove Si). A spring 52 is seated between the boss $6 and theboss 26 of cap 20 by means of a groove 5t?. The spring must be ofconducting material as it serves as an element of a circuit for thepassage of current through the switch.

Referring to PEG. l, the assembly of the device is as follows: The cap20 is inserted over the end of the housing by means of connector elementlo with O ring 24 in place. 'With the device held in upright position,with cap 2l serving as the bottom of the capsule, solution is pouredinto the capsule to fill it about two-thirds full. The piston 32 withspring 52 having one end seated in groove 50 is then inserted into thecapsule and the other end of the spring seated on boss 26. Before theinsertion of the piston 32 into the capsule, the pellet 37 is seated inthe seat 36. Cap 2@ is now brought into position for attachment toconnector 16. The end 29 of plunger 28 is inserted in the end of hole 56in the pellet 37 and the assembly of piston 32 and spring 52 compressedin the direction of cap 2l until threads i3 of connector 16 mate withthreads 22 of cap 20 and the cap 20 is then screwed into final position.

Referring again to FIG. l for a description of the completed assembly,it will be seen that piston 32 is biased in the direction of plunger 28and is held in biased position by the Contact of pellet 37 with the end29 of plunger 28. With the switch assembly in this position it will beseen that a continuous circuit path is provided from cap 20 throughspring 52, piston 32, flat springs 39-39 to points Llll-4l. lt will alsobe seen that a continuous circuit path is provided from cap Ztl to theend 29 of the 4contact area of plunger 2S.

The operation of the device is as follows: The capsule is inverted tobring the solution in contact with the pellet 37. When the pellet 37 isdissolved or sufficiently disintegrated to no longer withstand thebiasing force of spring 52, piston 32 will move in the direction ofplunger 28 so that the conducting end 29 of plunger 28 will contact thepoints Llll-il and complete a continuous circuit through the switchingdevice from cap 20 to cap 20. The conducting elements of the circuit arecap Ztl', biasing spring 52, piston 32, flat springs 39-39', points 41-41', plunger 29 and the cap 2d and they form a continuous circuit pathor conducting path. At this point of travel of piston 32 current willilow through the switching device with the device being a link in thecircuit or current path. As the contact points 4'1-41' are resilientlymounted by means of springs 39-39, the piston will continue to travelunder the biasing force of spring 52 in the `direction of plunger 2Suntil the contact points have passed beyond the conducting area 29 ofplunger 28 and come to rest on insulating member 30, the continuousvcircuit being broken as soon as the contact points dil-4l corne inContact on either side with insulating sleeve 30. It will be noted thatthe contact points il-031 now rest on the insulating sleeve 3@ and theend 29 of plunger 23 is seated in the pointed area of insulating liner35. The device is now ready for disassembly and recharging for re-useand can be used over and over. It will be noted that the switchingdevice sequentially changes from a safe condition as shown in FIG. l toa condition in which the circuit is closed as shown in dotted lines to afinal safety position as shown in FIG. 2. The time in which the circuitremains closed will, of course, depend upon the strength of spring 52and the consequent rate of travel of the piston as well as the size ofthe relative contact areas 29 of plunger 28 and contact points ll-4l.The switching device can be enclosed in a power-pac device with theconducting end caps Ztl-Ztl in conducting relationship with componentsof a circuit and the power-pac inserted in a conducting cable to be usedfor lifting, lowering explosives into a hole, etc. Thus assembled, theswitching device serves as a timing switch for a circuit and becomes alink in the circuit when the circuit is closed. It should be'mentionedthat the materials of the timing pellet 37 and the solution for it areso selected that no galvanic action is produced during the action of thesolution on the pellet or by the reaction products formed. The solutionis, of course, in `contact with the exposed surface of the pellet 37 andcornes in contactV with the interior surface of the pellet 37 bytravelingthrough channels 42 and bores 43 into the interior of the liner3S.

Various alternative equivalent structures and features to thosedisclosed will be apparent to those skilled in the art. For example, thepoints 41-41 and plunger 28 can be biased for relative movement towardeach other by other arrangements, such as, the piston being fixed andthe plunger being spring-biased toward it with the spring positionedbetween the end of the plunger and cap 20, or springs can be usedbetween both the plunger and the piston and the respective adjacent endcaps. Furthermore, as the points 41-41' constitute one' electricalterminal contact within the housing and the connecting area 29 of theplunger 28 constitutes another electrical terminal contact, the twoterminals which are -brought in contact to complete the circuit throughthe device can take various forms and are not limited to a switch gapand a plunger. For example, the piston can be replaced by anotherplunger hinged at its base to pass over contact area'? of plunger 28 andtravel on down to contact insulating sleeve 30. While the timing meansfor controlling the actuation of the switch to the closed position isdisclosed as a pellet which dissolves or disintegrates in the solution,other'timing means, such as, electrical timing means can be used. Theuse of the pellet and a solution in which it dissolves is exemplary ofthe preferred timing means.

VThe switching device of the invention can be used Without utilizing thesafety feature. For example, the time pellet 37 may be made ofconducting material, such as, metalized plastic, and the device used tobreak a circuit after a predetermined time. The safety feature is mostcommonly used in conjunction with the use of explosives. With aconducting pellet 4being used, theV circuit would be closed with theelements of the device in the position shown in FIG. l. After theconducting pellet has dissolved or disintegrated, the, circuit will bebroken and the piston will move relative to the plunger to place thecon- Vtact points 41-41 in contact with insulating sleeve 30 wherein thedevice will be in the FIG. 2.

While the combination of a solid pellet 37 and a solution for dissolvingit has been disclosed as a timing means, the pellet can obviously bedissolved ordisintegrated by other means, such as, gases, pressure, etc.The important thing is that there be no galvanic action created by thepellet and the solvent or the reaction products thereof, and thedisintegration or solution of the pellet be' controllable. As usedherein thel term .soluble includes the property of the material todissolve or disintegrate in gaseous Vand other mediums as well asliquids and the position shown in term solvent includes gaseous andother mediums as well as liquids. l I l A The switching device disclosedherein can be used in any circuit; however, it finds special applicationin bridge plugs, packers, selective timers,` electromagnetic fishingtools, retrieval apparatus, oil well equipment involving explosives,remote control switches, etc.

It is seen from the above description that a simple switching devicehavinga minimum of operating parts rhas been provided which can be usedin any type electrical circuit. The device has the advantage that'thetiming period can be reproducibly altered and controlledby vvarying thematerial of the time pellet and the solution and the characteristics ofthese two elements. It can also be varied by adjusting the strength ofthe spring 52 and by other means which will be obvious to those skilledin the art. The device provides a safety device insuring a current paththrough the device, thus eliminating theV use of external circuits andparts.

It will be understood that other modifications than those disclosed arepossible without departing from the spirit of the invention or the scopeof the claims.

I claim:

1. A switching device comprising, in combination: a housing ofinsulating material; an electrically conducting closure means at bothends of said housing; a first electrical terminal contact means in saidhousing connected to one of said closure means in electricallyconducting relationship; a second electrical terminal contact means insaid housing attached to said other closure means in electricallyconducting relationship and adapted to contact said first electricalterminal contact means in electrically conducting relationship; a timingelement of soluble material holding said terminal contact means out ofContact for a predetermined time; a solvent for said soluble element insaid housing; whereby upon elapse of said predetermined time saidterminal contact means come in contact and-a continuous conducting pathis established between said conducting closure means at both ends ofsaid housing. Y

2. The switching device of claim 1 in which at least one of saidterminal contact means is biased to move in the direction of the otherterminal contact means.

3. A switching device comprising, in combination: a housing ofinsulating material; an electrically conducting closure means at bothends of said housing; a first electrical terminal contact means in saidhousing connected to one of said closure means in electricallyconducting relationship and including a switch gap with terminal points;a second electrical terminal contact means in said hou-sing attached tosaid other closure means in electrically conducting relationship andadapted to contact and connect said terminal points of said switch gapin electrical conducting relationship; means for breaking electricallyconducting contact between said electrical terminal Vcontact means afterthey are in contact; and means for forcing said electrical terminalcontact means sequentially v in and out of electrically conductingcontact with each other; and timing means holding said terminal contactmeans out of contact with each other for a pre-determined time wherebyupon elapse of said pre-determined time said terminal Contact means comein contact and a continuous conducting path is established betweenv saidconducting closure means at both ends of said housing.

4. A switching device comprising, in combination: a housing ofinsulating material; an electrically conducting closuremeans at bothends of said housing; a iirst electrical terminal Contact means in saidhousing connected to one Vof said closure means in electricallyconducting relationship; a second electricallterminal contact means insaid housing Vattached to said other closure means in electricallyconducting relationship and adapted to contact said first electricalterminal contact means-in electrically conducting relationship; timingmeans holding said terminal contact means out of contact for apredetermined time; whereby upon elapse of said pre-determined time saidterminal contact means come in contact and a continuous conducting pathis established between said conducting closure means at both ends ofsaid housing; means for breaking electrically conducting Contact betweensaid electrical terminalV contact means after they are in contact, andmeans for .forcing said electrical terminal contact means sequentiallyin and out of electrically conducting contact with each other.

5. The switching device of claim 4 in which said timing means is anelement of soluble material.

6. A switching device comprising, in combination: a housing ofinsulating material; an electrically conducting closure means at bothends of said housing; a first electrical terminal contact means in saidhousing connected to one of said closure means in electricallyconducting relationship and including a switch gap with terminal points;a second electrical terminal contact means in said housing attached tosaid other closure means in electrically conducting relationship andincluding a conducting plunger having a conducting contact area adaptedto contact and connect the contact points of said switch gap and havingan insulating area distal to said contact area positioned to besequentially contacted by said contact points following their contactwith said conducting contact area; at least one of said electricalterminal contact means being biased to move in the direction of theother terminal contact means; said electrical terminal contactmeansconstructed to be held apart for a predetermined time by timing meansand to move in Contact with each other after elapse of saidpredetermined time.

7. The switching device of claim 6 including timing means holding saidterminal contact means out of contact for a predetermined time.

8. A switching device comprising, in combination: a housing ofinsulating material; an electrically conducting closure means at bothends of said housing; a hollow piston in saidhousing carrying a firstelectrical terminal contact means including a switch gap having at leasttwo terminal points extending into the hollow of said piston and beingconnected to one of said closure means in electrically conductingrelationship; a second electrical terminal contact means in said housingattached to said other closure means in electrically conductingrelationship and adapted to contact said iirst electrical terminalContact means in electrically conducting relationship; an electricallyconducting biasing spring between the end of said piston distal to theother of said terminal contact means and one of said closure means;timing means holding said terminal contact means out of contact for apredetermined time; whereby upon elapse of said predetermined time saidterminal contact means come in contact and a continuous conducting pathis established between said conducting closure means at both ends ofsaid houslng.

9. The switching device of claim 8 in which said timing means is anelement of soluble material.

10. A switching device comprising, in combination: a housingofinsulating material; an electrically conducting closure means at bothends of said housing; a piston carrying a rst electrical terminalcontact means in said housing connected to one of said closure means inelectrically conducting relationship; a second electrical terminalcontact means in saidV housing attached to said other closure means inelectrically conducting relationship and adapted to contact said iirstelectrical terminal contact means in electrically conductingrelationship; a biasing means betweenthe end of said piston distal tothe other of said terminal contact means and one of said closure means;timing means holding said terminal contact means out of contact yfor apredetermined time; whereby upon elapse of said predetermined time saidterminal contact means come in contact and a continuous conducting pathis established between said conducting closure means at both ends ofsaid housing; and means associated with one of said terminal contactmeans for breaking electrically conducting contact between saidelectrical terminal contact means after they are in contact, saidbiasing means being operative to force said electrical terminal contactmeans sequentially into electrical Contact with each other and intoposition in which said breaking means is eective to break saidelectrically conducting Contact.

11. The switching device of claim 10 in which said timing means is anelement of soluble material.

12. The switching device of claim 6 in which said insulating area iscomprised of a sleeve of insulating material.

13. The switching device of claim 6 including a piston carrying one ofsaid terminal contact means and a biasing means between the end of saidpiston distal to the other of said terminal contact means and one ofsaid closure means.

14. The switching device of claim 8 in which said terminal points areresiliently mounted.

15. The switching device of claim 10 in which said breaking means is aninsulating sleeve.

16. A switching device comprising: a housing of insulating materialclosed at both ends with caps of electrically conducting material; aplunger of electrically conducting material mounted internally of saidhousing in electrically conducting relationship with one of said capsand provided with an insulating sleeve distal to its free end; anelectrode piston in said housing in electrically conducting relationshipwith the other of said caps and having an internal chamber; a pair ofopposed spring biased conducting elements supported by said piston inelectrically conducting relationship therewith extending -through thewall of said piston into said chamber and forming a switch gap for anelectrical circuit; biasing means between the end of said piston -distalto said plunger and said other of said caps biasing the piston in thedirection of said plunger; and a pellet of soluble material supported atthe other end of said piston in contact with the free end of saidplunger and holding said piston in biased position.

17. The switching device of claim 16 including an insulating sleeve insaid chamber.

18. The switching device of claim 17 in which said piston and saidbiasing means are of electrically conducting material.

19. The switching device of claim 16 in which said soluble element is ofnon-conducting material.

20. The switching device of claim 16 in which said soluble element is ofa conducting material.

21. The switching device of claim 1 in which said element is made ofpolystyrene and said solution is methylene chloride.

22. A `switching device comprising, in combination; a housing ofinsulating material; an electrically conducting closure means at bothends of said housing; a rst electrical terminal contact means in saidhousing connected to one of said closure means in electricallyconducting relationship; a second electrical terminal contact means insaid housing attached to said other closure means in electricallyconducting relationship and adapted to contact said rst electricalterminal Contact means in electrically conducting relationship, at leastone of said terminal contact means being biased to move in the directionof the other contact terminal means; a timing element of solublematerial located between said terminal contact means and holding saidterminal contact means out of Contact for a predetermined time; wherebyupon elapse of said predetermined time said terminal contact means comein contact and a continuous conducting path is established between saidconducting closure means at both ends of said housing.

23. A switching device comprising, in combination: a housing ofinsulating material; an electrically conducting closure means at bothends 0f said housing; a rst electrical terminal contact means in saidhousing connected to one of said closure means in electricallyconducting relationship; a second electrical terminal contact means insaid housing attached to said other closure means Vin electricallyconducting relationship and adapted to contact said first electricalterminal Contact means in electrically conducting relationship, at leastone of said terminal contact means being biased to move in the directionof the other contact terminal means; said electrical terminal contactmeans constructed to be held apart for a predetermined time by timingmeans and to move in Contact with each other after elapse of saidpredetermined References Cited by the Examiner time; means for breakingelectrically conducting Contact UNITED STATES PATENTS between saidelectrical terminal contact means after they are in contact; and meansfor forcing said electrical ter- 3,179,770 minal contact meanssequentially in and out of electrically conducting contact with eachother.

24. The switching device of claim 23 including timing BERNARD A.GILHEANY, Primary Examiner.

means holding said terminal contact means out of Contact R N ENVALL JRAssistant Exam-ne. for a predetermined time.

4/1965 Demaret 20G-117 XR

1. A SWITCHING DEVICE COMPRISING, IN COMBINATION: A HOUSING OFINSULATING MATERIAL; AN ELECTRICALLY CONDUCTING CLOSURE MEANS AT BOTHENDS OF SAID HOUSING; A FIRST ELECTRICAL TERMINAL CONTACT MEANS IN SAIDHOUSING CONNECTED TO ONE OF SAID CLOSURE MEANS IN ELECTRICALLYCONDUCTING RELATIONSHIP; A SECOND ELECTRICAL TERMINAL CONTACT MEANS INSAID HOUSING ATTACHED TO SAID OTHER CLOSURE MEANS IN ELECTRICALLYCONDUCTING RELATIONSHIP AND ADAPTED TO CONTACT SAID FIRST ELECTRICALTERMINAL CONTACT MEANS IN ELECTRICALLY CONDUCTING RELATIONSHIP; A TIMINGELEMENT OF SOLUBLE MATERIAL HOLDING SAID TERMINAL CONTACT MEANS OUT OFCONTACT FOR A PREDETERMINED TIME; A SOLVENT FOR SAID SOLUBLE ELEMENT INSAID HOUSING; WHEREBY UPON ELAPSE OF SAID PREDETERMINED TIME SAIDTERMINAL CONTACT MEANS COME IN CONTACT AND A CONTINUOUS CONDUCTING PATHIS ESTABLISHED BETWEEN SAID CONDUCTING CLOSURE MEANS AT BOTH ENDS OFSAID HOUSING.